Re: [DNA] MUST Store Lifetime and Last Refresh time?(draft-pentland-dna-protocol-00.txt)

[Greg Daley <greg.daley@eng.monash.edu.au>]

Hi Erik,

Erik Nordmark wrote:
[cut]
>>    3.  Valid lifetime
>>
>>    4.  Time last refreshed"
>>
>> In my (existing) implementation I'm storing the expiry time
>> of the prefix (which is calculated based on the valid lifetime
>> at the RA reception time).
> 
> 
> Is this for #3 above? Are you also storing #4?

I think that the issue was basically that the term "store"
means "allocate space for" to me.

When that's combined with a MUST, I have to change data structures...

>> Is this insufficient?
> 
> 
> Storing the expiry time for the valid lifetime is what's needed for #3.

Ok. That clarifies things.

[cut]
> 
> The intent is to provide enough *conceptual* data structure descriptions 
> so that the protocol can be described in detail, but not constrain how 
> an implementation actual does things as long as the externally visible 
> behavior of the implementation is consistent with the specification.
> 
> There is text in section 5 in RFC 2461 which says this, so perhaps we 
> can just borrow that text.

I see (in 5.1 conceptual data structures).

"Prefix List entries are created from information received in Router
  Advertisements.  Each entry has an associated invalidation timer
  value (extracted from the advertisement) used to expire prefixes
  when they become invalid"

This approach sounds good to me.

Thanks,

Greg